Abstract: In order to achieve reasonable, accurate, real-time protection switching for business and clock of synchronous digital hierarchy self-healing ring, a scheme to implement protection switching based on automatic protection switching protocol and synchronization status byte S1 in the section overhead is proposed.Switching commands from network management station, alarms triggering switchover and K1, K2 bytes transmitted from upstream network elements are treated separately, to achieve the protection switching of the business and lead to corresponding clock switching.Test for typical operation instances, the validity and real-time performance of the scheme are verified.